My present invention relates to a method for automatically separating or parting a roving upon the removal of a fully wound bobbin from a roving frame, especially a flyer frame in which the roving is delivered to the bobbin by a pressing finger pad on a flyer and the separation or parting of the roving is effected between the pressing finger pad and the bobbin periphery.
There are numerous techniques which have been developed for the parting of the roving between the pressing finger of a flyer of a roving frame and full roving bobbin. During the winding of the bobbin, the bobbin core or tube on the spindle is rotated and the roving is fed, usually from a drafting frame through the flyer and a pressing finger on the flyer to the pressing finger tube or bed at the tip or free end of the pressing finger, from which the roving is delivered to the tube and is wound up in a bobbin. The relative axial movement of the flyer and the spindle build a generally cylindrical body of winding in the bobbin which is flanked between conical windings at the upper and lower ends thereof.
German patent document DE 196 31 756 A1 describes one of the several known techniques for separating or parting the roving between the pressing finger of a flyer and the full roving bobbin. In this system, a piece of the roving has a relatively high number of rotations per unit length generated therein by an increase in the ratio of the flyer speed to the roving feed rate from the drafting frame in the formation of the last layer of the roving on the bobbin. The roving length of greater strength produced by controlling the flyer speed and the delivery rate of the roving from the drafting frame is followed by a reverse rotation of the bobbin to relieve the twist between the pressing finger bed and the bobbin. Whereupon, by lowering of the bobbin carriage into the bobbin removal position, the roving is broken usually at the relaxed location adjacent the pressing finger bed.
The drawback of this approach is that the location of the break in the roving on the bobbin body is not fixed and varies widely from bobbin to bobbin. Furthermore, the length of roving and hanging from the pressing finger bed also may vary widely from case to case. This lack of relatively precise break locations from bobbin to bobbin and station to station constitutes a significant drawback in the handling of the bobbin subsequently and in the winding of new bobbins on empty tubes.
It is, therefore, the principal object of the present invention to provide an improved method of breaking a roving between the pressing finger bed and the fully wound bobbin whereby the aforementioned drawbacks are avoided.
Another object of this invention is to improve the precision of parting of a roving in a flyer frame system for producing full roving bodies whereby the location of the break on the body of the bobbin and the length of roving remaining on the pressing finger bed are both determined with a higher degree of reliability and reproducibility than has hitherto been the case.
Still another object of the invention is to provide a method of breaking the roving supplied to a bobbin, upon the removal thereof such that a predetermined length of roving remains free on the pressing finger of the flyer.
These objects are attained, in accordance with the invention by first generating at least a half turn of the roving and a roving reserve above the bobbin, then unwinding the roving reserve by rotating the bobbin backwardly simultaneously with a vertical movement of the pressing finger bed along the bobbin axis to generate a weakened spot along the roving leading from the pressing finger bed by partial untwisting, then moving the pressing finger bed by a certain amount along the periphery of the bobbin, and drawing the roving taut and parting the roving in the region of the weak spot by movement of the pressing finger bed.
This system provides the advantage that the desired weak spot will form with a high degree of reliability over a predetermined segment of the roving and that after the separation an end of the desired length will remain on the pressing finger bed.
According to a feature of the invention, the reserve is formed in turns on the tube above the bobbin winding, i.e. above the upper winding cone. The reserve below the fastening turns can be treated as being formed from three segments, namely, a first segment from an upper edge of the upper winding cone to the lower edge thereof at the junction between the upper winding cone and the cylindrical body of the bobbin, a second roving segment from the lower edge of the upper winding cone to the aforementioned weakened points and a third roving segment from the weakened point to the pressing finger bed, whereby this third segment has a length corresponding to the length which is to remain hanging from the pressing finger upon removal of the full bobbin.
The reverse rotation of the roving bobbin generates a false twist which increases the number of rotations per unit length in the first segment and reduces the number of twists per unit length in the second and third segments. The movement of the pressing finger bed to a further point along the body of the bobbin can make the second and third segments of substantially equal length. The segment between the break and the finger can be strengthened by increasing the number of twists or rotations per unit length. The distance between the two locations along the periphery of the bobbin body through which the pressing finger bed is moved can correspond to the number of rotations or twists per unit length in the segment between the break location and the pressing finger bed. Finally the movement of the pressing finger bed in the same direction to a further location along the body of the bobbin effects the separation.
More particularly, the method of automatically parting a roving upon removal of a full roving bobbin from a roving flyer frame in which the roving bobbin is wound on a roving tube with upper and lower winding cones having a wound body between them as the tube is rotated and the roving is delivered by a flyer from a pressing finger bed of the flyer resting on a surface of the wound body of the bobbin comprises:
(a) generating at least half a turn of roving and a roving reserve above the bobbin by a forward rotation of the bobbin following completion of the bobbin and while retaining the roving with the pressing finger bed;
(b) unwinding the roving reserve by a reverse rotation of the bobbin to form a weakened location along the roving at a certain distance from the pressing finger bed;
(c) moving the pressing finger bed by a predetermined amount along a periphery of the bobbin; and
(d) pulling on the roving by movement of the pressing finger bed, thereby parting the roving at the location.